The present invention relates to an optical head apparatus for recording or reproducing information in a disc drive for driving optical discs such as a digital video disc (DVD) and a compact disc (CD), particularly to a substrate unit for an optical head preferably applied to a so-called integrated optical unit (hereinafter referred to as IOU) in which a laser diode (hereinafter referred to as LD), a photodiode (hereinafter referred to as PD), a holographic optical element (hereinafter referred to as HOE), and the like are integrated, and to a manufacturing method of the substrate unit.
As well known, either an LD or PD for use in an optical head apparatus has heretofore been prepared by a manufacturing method similar to a method of forming an element pattern of a semiconductor on a silicon (Si) substrate or a gallium arsenic (GaAs) substrate.
In this case, an LD is constituted to be irradiated with a laser light substantially in parallel to the surface of the substrate with the LD to be formed thereon. Moreover, the PD is constituted so as to receive light vertically incident upon the surface of the substrate with the PD to be formed thereon.
Therefore, in the conventional optical head apparatus, an optical disc is irradiated with the laser light from the LD, and the reflected light is received by the PD. This constitution needs to have a three-dimensional structure in which the LD and PD are disposed adjacent to each other, and the substrate surface with the PD formed thereon is disposed substantially at right angles to the substrate surface with the LD formed thereon.
Additionally, a concrete constitution example of the optical head apparatus having a structure in which LD and PD are arranged in a three-dimensional positional relation in this manner is disclosed, for example, in Jpn. Pat. Appln. KOKAI Publication No. 110796/1999.
Additionally, in order to perform high-reliability recording/reproducing with respect to the optical disc, it is important to accurately drive respective servo systems such as tracking and focus, and it is necessary to set the position relation between the LD and PD with a high precision of 10 xcexcm or less.
Moreover, the substrate with the LD formed thereon is electrically connected to the substrate with the PD formed thereon by wire bonding. In this case, three-dimensional wire bonding needs to be performed.
However, when the LD and PD are subjected to mutual position adjustment, wire bonding, and the like in three dimensions with such high precision, the operation becomes very difficult and intricate. This causes a problem that operation efficiency is deteriorated.
To solve the problem, the present invention has been developed in consideration with the circumstances, and an object thereof is to provide a substrate unit for an optical head apparatus, in which the LD and PD can be disposed on the same two-dimensional plane, thereby an operation for positioning the LD and PD is facilitated, and an operation efficiency of wire bonding can also be enhanced.
Moreover, an object of the present invention is to provide a manufacturing method of the substrate unit for the optical head apparatus, in which the substrate unit for the optical head apparatus can be manufactured with high precision and satisfactory mass productivity.
According to the present invention, there is provided a substrate unit for an optical head apparatus, comprising:
a light emitting element attachment surface for attaching a light emitting element which emits a laser light substantially in parallel to the surface with the element to be attached thereto;
a light reflecting surface for changing a direction of a light axis of the laser light emitted from the light emitting element attached to the light emitting element attachment surface by a predetermined angle by reflection; and
a light detecting element attachment surface, formed on the same two-dimensional plane as a plane of the light emitting element attachment surface, for attaching a light detecting element which receives a light incident from the outside.
According to the aforementioned constitution, since the light emitting element and light detecting element can be disposed on the same two-dimensional plane, an operation for positioning the light emitting element and light detecting element can be facilitated, and an operation efficiency of wire bonding can also be enhanced.
Moreover, according to the present invention, there is provided a manufacturing method of a substrate unit for an optical head apparatus, comprising:
a step of forming a plurality of light reflecting surfaces on one plane of a first member to be processed formed substantially in a rectangular parallelepiped shape;
a step of attaching one plane of a second member to be processed formed substantially in the rectangular parallelepiped shape to the plane of the first member to be processed with the plurality of light reflecting surfaces formed thereon in the forming step, disposing an adhesive medium in a portion other than the light reflecting surface, and forming a bonded block in which the first and second members to be processed are connected to each other;
a step of cutting the bonded block formed in the forming step at a predetermined angle with respect to the light reflecting surface, and dividing the bonded block into a plurality of blocks so that one light reflecting surface is included in each block; and
a step of disposing a cut surface of the block obtained in the forming step as a reference surface of a processing, and forming the substrate unit from the block, comprising a light emitting element attachment surface for attaching a light emitting element which emits a laser light to the light reflecting surface, and a light detecting element attachment surface for attaching a light detecting element, formed on the same two-dimensional plane as the light emitting element attachment surface, for receiving light incident from the outside.
According to the manufacturing method, the bonded block formed by connecting the second member to be processed to the first member to be processed with the plurality of light reflecting surfaces formed thereon is cut at the predetermined angle with respect to the light reflecting surface and divided into the plurality of blocks. When the cut surface of the block is disposed as the reference surface of the processing, the substrate unit including the light emitting element attachment surface and light detecting element attachment surface is formed from the block. Therefore, the substrate unit for the optical head apparatus can be manufactured with the high precision and satisfactory mass productivity.